1. Field of the Invention:
This invention relates to an elasto-plastic damper for use in a building structure, and, more particularly, to an elasto-plastic damper which is primarily installed in the frame of a structure to attenuate vibrations of the structure caused by earthquake tremors or the like.
2. Description of the Prior Art:
Prior art dampers used for absorbing vibrational energy of structures include elasto-plastic dampers utilizing elasto-plastic hysteresis attenuation, viscous dampers such as oil dampers which utilize viscosity and depend upon response speed at the time of occurrence of an earthquake, and friction dampers.
Among the above dampers, the elasto-plastic damper is more widely used because this damper requires no maintenance and provides a high degree of energy absorbability. The elasto-plastic damper generally takes the form of a steel bar, which is vertically supported in cantilever relation to either an upper or lower structure which are separated by a vibration isolation mechanism.
The steel bar damper displays great energy absorbability and stability when it is subjected to a repetitive force due to a relative horizontal shifting of the upper and lower structures. Since steel bar dampers are installed in order to absorb the vibrational energy of the entire upper structures, they are, of necessity, large in scale. In addition, since steel bar dampers are conventionally used in combination with multi-layer rubber supports, or like vibration isolation mechanisms, there are only a limited number of locations in a building structure where steel bar dampers may be installed.